Machines such as, for example, wheel loaders, motor graders, dump trucks, and other types of heavy machinery are used for a variety of tasks. These machines generally include a power source, which may be, for example, an engine, such as a diesel engine, gasoline engine, or gaseous fuel-powered engine that provides the power required to complete the tasks. To efficiently perform these tasks, the machines utilize a transmission that is capable of transmitting the torque generated by the engine over a wide range of speeds. The transmission may include, for example, a mechanical transmission, an electric transmission, or a hydraulic transmission. These transmissions may be capable of providing a desired output torque at a desired speed within its operating range by changing a ratio of the transmission.
The machines also typically include traction devices driven by the transmission to engage the ground in order to impart horizontal driving motion to the machine. In certain machines, known as “track-type tractors” or “crawlers”, the driven traction devices include one or more tracks driven by a sprocket assembly of the machine. Under normal operation, these tracks are preferably in power-transmitting engagement with the ground. However, in some situations such as loading, unloading, uneven loading, or traveling over inconsistent, inclined, or soft or loose terrain, it may be possible for the driven traction devices to slip or move faster than a traveling speed of the machine. Slipping can decrease the efficiency of the machine, increase wear of the tracks, decrease life of the drive train components (e.g., engine, transmission, sprockets, etc.), and possibly result in unexpected or undesired movement of the machine.
Traditionally, slip of machine driven traction devices has been addressed by determining that slip is occurring and then reducing a torque applied to the tracks. For example, U.S. Pat. No. 6,799,652 (the '652 patent) issued to Nissen et al. on Oct. 5, 2004 discloses a method of reducing slip of a driving wheel of an industrial truck. The method includes comparing a circumferential measured speed of the wheel to a set point and calculating slip based on the comparison. If slip is occurring, the torque applied to a driving motor of the industrial truck is reduced. In this manner, wear of the truck may be minimized and efficiency increased.
Although the method of the '652 patent may minimize wheel slip, the manner in which it detects slip may be complex and unreliable. In particular, because the method minimizes slip by measuring a speed and performing calculations, the process may be complicated and time consuming. Moreover, because the method requires the implementation of expensive sensing equipment in locations vulnerable to damage, it may be susceptible to malfunction.
The present disclosure is directed towards overcoming one or more of the problems as set forth above.